1. Field of the Invention
The present invention relates to a C-type underbracing installed at bottom end of the utility pole for anchoring. More particularly, the C-type underbracing formed enlarged end portions to facilitate installation on the utility pole by using a crane auger. The body segment between the enlarged end portions is formed C-shape with thinner than the body thickness. Thus, the enlarged end portions of the C-type underbracing will increase the contacting area with the covered soils to improve the resistance and enhance the supporting tension to the utility pole.
2. Description of the Related Art
For example, Korean Patent Application No. 2006-112100, filed by the applicant of the present invention, discloses a utility pole underbracing for utility pole construction. In this underbracing, as shown in FIG. 1, the overall shape of the underbracing 100 is roughly a half toroid. The inner semi-circle surface 101 conforms to the cross-section shape of a utility pole, and the outer semi-circle 102 has a diameter of about 0.8 m. Although this underbracing has a shape different from the conventional bar-type utility pole underbracing, the surface area in contact with soil after mounting is almost the same.
However, the volume is smaller so the weight is less than the conventional rectangular underbracing. Therefore, when excavating the pit for burying the pole during utility pole construction, the excavation volume is greatly reduced compared to the conventional rectangular underbracing, and since it is easier to handle, construction efficiency and workability are improved.
Furthermore, on the outer circumference of the semi-circular utility pole underbracing there are a U-bolt inserting hole 103 used for mounting the underbracing and a slot 104 which increases the cohesion with soil under the earth surface. The inner circumference varies, made according to the curvature specification of the utility pole, resulting in better install ability and increased strength of underbracing.
However, since the above mentioned semi-circular utility pole underbracing is a C-type solid bound by curved surfaces, the adherence area with soil is not sufficient, so the coherence between the pole and the soil is not satisfactory. In the case of assembling with U bolts, the U-bolt insertion hole is of through-hole shape, so the dimensions of the insertion hole and the U bolt should match, which causes difficulty in logistics management, and frictional interference in construction.
Also, since the above mentioned conventional semi-circular utility pole underbracing is relatively large and heavy (95 kg), it is difficult to handle and there are many difficulties with fabrication and transportation. When installing a large and heavy object in the utility pole burial pit by using an extra crane, the process for binding the underbracing to the crane is complicated, and it is also very difficult and toilsome to disconnect the bindings again.
Therefore, the actual site has dire need for an improved utility pole underbracing that has better adherence resistance force with the soil and also is easier to fasten to the pole.